XADM: Text Attachments Appear Corrupted

• Microsoft Exchange Server versions 5.0 and 5.5

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information on how to do this, view the "Restoring the Registry" online Help topic in Regedit.exe or the "Restoring a Registry Key" online Help topic in Regedt32.exe.

SYMPTOMS

Some messages with attachments sent by the Exchange Server Internet Mail Service may be encoded with Quoted-Printable encoding. If the message is received by an older MIME-compliant client, the attachment may be shown as corrupted text.

CAUSE

Exchange Server 4.0 uses Base64 encoding; Exchange Server 5.0 and 5.5 Internet Mail Service use Quoted-Printable encoding for text attachments. Because many older POP3 clients are still not Quoted-Printable aware, they may fail to decode the attachment properly.

RESOLUTION

To resolve this problem:

• Install the provided hotfix and add the registry key shown below.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

1. Start Registry Editor (Regedt32.exe or Regedit.exe as appropriate for

1. Go to the following key in the registry:

         HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Service\MSExchangeIS
         \ParametersSystem\InternetContent
   

2. On the Edit menu, click Add Value and use the following entry:

         Value Name: ForceBase64
         Data Type:  REG_DWORD
         Value:      0x1
   
   

3. Exit Registry Editor.

STATUS

Microsoft has made this fix module for Microsoft Exchange Server, version 5.0 and 5.5. A supported fix is now available, but has not been fully regression- tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

MORE INFORMATION

This fix allows you to add a new registry key so you can choose Base64 encoding. The new registry entry is called "ForceBase64."